What is a Bong-Bitcoin, or ᵇTBC? It is 42.94967296 BTC.

42 is the answer to the universe. Coincidence?

What is Bitcoin? Bitcoin is a decentralized digital currency based on an open-source, peer-to-peer internet protocol.

Basically, bitcoins are "mined" by computer processing power by solving blocks, then adding them to the block chain. When a block is solved, bitcoins are harvested. Currently the reward is 25BTC, which halves every 210,000 blocks. The maximum number of bitcoins that can be harvested is 20,999,999.9769; the very last bits won't be mined until 2140. See the Controlled supply wiki page for more info.

The block chain is a register of every transaction on the bitcoin network. Every user downloads a copy of this register, so everyone verifies multiple times every transaction. The only way to verify the transactions is by solving the blocks. This way, no one can hack into a central server, for example, and steal financial information and money.

So people mine bitcoins. Bitcoins are spent back and forth, which adds to the transaction register. Blocks are solved, verifying transactions and adding to the chain, which releases more bitcoins, which people spend. It's a wonderful circle.